Programming the Use of Main Outfall Drain Water for Irrigation

Abstract

The use of saline drainage water for irrigation has expanded due to the decrease and contamination of fresh water resources. The current study aims to evaluate the water of the Main Outfall Drain (MOD), which collects the water of the main drainage channels in the central and southern of Iraq, and huge quantities of moderate-saline water flow to the Arabian Gulf. The MOD water discharges and concentrations data for the years (2019-2021) were collected and compared with similar parameters of data that had collected for the period (1994-1996). It was noted that the discharge increased to the estuary downstream, the salinity of the MOD water is lower than it was twenty-five years ago during the period (1994-1996) at rates of about (34%), at a rate of 1 ds/m every one decades. This encourages the investment of this water in planting the sides of MOD with salt-tolerant trees. Important modifications were made to the Furat-Ujaj Program which was constructed to use saline water for irrigation. The different effects of saline water on soil and plants were formulated as a matrix of three saline’s effects versus five field conditions. Visual Basic language was used to build the modified program that aimed to use the largest possible amount of MOD water for irrigation after mitigating the toxic effects by diluting saline water with fresh water taken from the adjacent river to the project. The program begins to calculate the mitigation of the toxicity effects, and then the relative yield of the selected crops will be calculated. If the production is below the economically acceptable limit, another 5% of the river water will be added to mitigate, and the dilution process continues until the percentage of the river water become 80%. If the required production is not achieved, the program instructs to irrigate this crop with the river water only. The study found the possibility of planting a green belt with an average width of more than 9 km of palm and olive trees on both sides of MOD. Green belt of Palm and Olive is planted according to the concept of rainwater harvesting to reduce salinity within the root zone without the need for the river water. This green strip can contribute to improving the environment in the center and south of the country.